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This List of echinoderm orders concerns the various classes and orders into which
taxonomists In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given ...
categorize the roughly 7000 extant species as well as the extinct
species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
of the exclusively marine phylum
Echinodermata An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea ...
.


Subphylum

Crinozoa Crinozoa is a subphylum of mostly sessile echinoderms, of which the crinoids, or sea lilies, are the only extant members. Crinozoans have an extremely extensive fossil history, which may or may not extend into the Precambrian (provided the eni ...


Class

Crinoidea Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which ar ...

* Subclass Articulata (540 species) ** Order
Bourgueticrinida Bourgueticrinida is an order of crinoids that typically live deep in the ocean. Members of this order are attached to the seabed by a slender stalk and are known as sea lilies. While other groups of crinoids flourished during the Permian, bourgu ...
** Order
Comatulida Comatulida is an order of crinoids. Members of this order are known as feather stars and mostly do not have a stalk as adults. The oral surface with the mouth is facing upwards and is surrounded by five, often divided rays with feathery pinnules ...
** Order
Cyrtocrinida Cyrtocrinida is an order of sea lilies which contains two suborders and three families. Characteristics Members of this order have stems consisting of a single skeletal unit or a very small number of units. There are no cirri, and the expanded b ...
** Order Hyocrinida ** Order Isocrinida ** Order
Millericrinida Millericrinida is an order of articulate crinoids that originated in the Anisian In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million ...
* Subclass †
Flexibilia Flexibilia is a superorder of specialized Paleozoic (Middle Ordovician to Permian) crinoids. They exhibited a conserved body plan and consistent suite of characteristics throughout their long history. Previously considered a subclass with unclea ...
* Subclass † Camerata * Subclass †
Disparida Disparida is an parvclass of extinct marine animals in the class Crinoidea. Disparids are a speciose and morphologically diverse group of crinoids distinguished by their monocyclic calyx and slender arms without pinnules. They range from the Ea ...
Image:Comaster schlegelii.JPG, '' Comaster schlegelii'' (
Comatulida Comatulida is an order of crinoids. Members of this order are known as feather stars and mostly do not have a stalk as adults. The oral surface with the mouth is facing upwards and is surrounded by five, often divided rays with feathery pinnules ...
) Image:Holopus 2.jpg, ''
Holopus ''Holopus'' is a genus of echinoderms belonging to the family Holopodidae. The species of this genus are found in Central America, Pacific Ocean (near Australia). Species: *''Holopus alidis'' *''Holopus mikihe'' *''Holopus rangii ''Holopus' ...
sp.'' (
Cyrtocrinida Cyrtocrinida is an order of sea lilies which contains two suborders and three families. Characteristics Members of this order have stems consisting of a single skeletal unit or a very small number of units. There are no cirri, and the expanded b ...
) Image:Encrinus liliiformis 4.JPG, ''
Encrinus liliiformis ''Encrinus'' is an extinct genus of crinoids, and "one of the most famous". It lived during the Late Silurian-Late Triassic, and its fossils have been found in Europe. History Fossils of ''Encrinus'' went by several names in Germany before the ...
'' ( Encrinida) Image:Calamocrinus diomedæ (Plate XXVIII) BHL4232451.jpg, '' Calamocrinus diomedae'' ( Hyocrinida) Image:Proisocrinus ruberrimus.jpg, '' Proisocrinus ruberrimus'' ( Isocrinida) Image:Liliocrinus polydactylus MHNT.jpg, '' Liliocrinus polydactylus'' (
Millericrinida Millericrinida is an order of articulate crinoids that originated in the Anisian In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million ...
)


Class

Paracrinoid Paracrinoidea is an extinct class of blastozoan echinoderms. They lived in shallow seas during the Early Ordovician through the Early Silurian. While blastozoans are usually characterized by types of respiratory structures present, it is not clea ...
ea †

No orders, 13 to 15 genera are known. * order Comarocystitida † ** ?Family Heckeritidae † *** '' Heckerites'' † ** Family Amygdalocystitidae † *** '' Achradocystites'' † Volborth, 1870 *** '' Amygdalocystites'' † Billings, 1854 (= ''Ottawacystis'') (?= ''Billingsocystis'') *** '' Oklahomacystis'' † Parsley & Mintz, 1975 (Bassler, 1943) *** '' Ovulocystites'' † Frest et al., 1980 ** Family Comarocystitidae † Balther, 1899 *** '' Comarocystites'' † Billings, 1854 *** '' Implicaticystis'' † *** '' Sinclairocystis'' † * order Platycystitida † ** Family Platycystitidae † *** '' Canadocystis'' † (= ''Sigmacystis'') *** '' Platycystites'' † ** Family Malocystitidae † *** '' Malocystites'' † *** '' Wellerocystis'' † ** Family Bistomiacystitidae † *** '' Bistomiacystis'' † Doubtful paracrinoids: * ''Columbocystis'' * ''Foerstecystis'' * ''Springerocystis'' * ''Ulrichocystis'' * ''Paleocystites'' * ''Allocystites''


Class

Cystoidea Cystoidea is a class of extinct crinozoan echinoderms, termed cystoids, that lived attached to the sea floor by stalks. They existed during the Paleozoic Era, in the Middle Ordovician and Silurian Periods, until their extinction in the Devonian ...
†

* order Aristocystitida † * order Asteroblastida † * order Glyptosphaeritida † * order Sphaeronitida †


Class

Edrioasteroidea Edrioasteroidea is an extinct class of echinoderms. The living animal would have resembled a pentamerously symmetrical disc or cushion. They were obligate encrusters and attached themselves to inorganic or biologic hard substrates (frequently h ...
†

* order Edrioasterida * order
Isorophida Isorophida (the isorophids) is an extinct order of prehistoric echinoderms in the class Edrioasteroidea Edrioasteroidea is an extinct class of echinoderms. The living animal would have resembled a pentamerously symmetrical disc or cushion. The ...


Subphylum

Asterozoa The Asterozoa are a subphylum in the phylum Echinodermata. Characteristics include a star-shaped body and radially divergent axes of symmetry. The subphylum includes the class Asteroidea (the starfish), the class Ophiuroidea (the brittle star ...


Class Ophiuroidea (

Brittle star Brittle stars, serpent stars, or ophiuroids (; ; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the sea floor using their flexible arms for locom ...
s)

** Order
Euryalida The Euryalida are an order of brittle stars, which includes large species with either branching arms (called "basket stars") or long and curling arms (called "snake stars"). Characteristics Many of the species in this order have characteristi ...
** Order
Ophiurida The Ophiurida are an order of echinoderms within the class Ophiuroidea. It includes the vast majority of living brittle stars. Characteristics Ophiurida have bursae for respiration and excretion, and dorsal and ventral arm shields are present a ...
** Order
Amphilepidida Amphilepidida is an order of echinoderms belonging to the class Ophiuroidea. Families: * Amphilepididae * Amphilimnidae * Amphiuridae * Hemieuryalidae * Ophiactidae * Ophiolepididae * Ophionereididae Ophionereididae are a family of brittle st ...
** Order
Ophiacanthida Ophiacanthida is an order of echinoderms belonging to the class Ophiuroidea. Families: * Ophiodermatina Ljungman, 1867 ** Ophiodermatidae ** Ophiomyxidae ** Ophiopezidae ** Ophiocomidae Ophiocomidae are a family of brittle stars of the subo ...
** Order Ophioleucida ** Order
Ophioscolecida Ophioscolecida is an order of echinoderms belonging to the class Ophiuroidea. Families: * Ophiohelidae Ophiohelidae is a family of echinoderms belonging to the order Ophioscolecida. Genera: * '' Ophiohelus'' Lyman, 1880 * '' Ophiomyces'' L ...
Image:Basket star feeding at night at the Red Sea.JPG, ''
Astroboa nuda ''Astroboa nuda'' is a type of basket star from Gorgonocephalidae family. Its large arms (up to armspread) are highly branched. It inhabits reef slopes exposed to current in diverse places such as the Red Sea The Red Sea ( ar, البح� ...
'' (
Euryalida The Euryalida are an order of brittle stars, which includes large species with either branching arms (called "basket stars") or long and curling arms (called "snake stars"). Characteristics Many of the species in this order have characteristi ...
) Image:Ophiura ophiura.jpg, ''
Ophiura ophiura ''Ophiura ophiura'' or the serpent star is a species of brittle star in the order Ophiurida. It is typically found on coastal seabeds around northwestern Europe. Description ''Ophiura ophiura'' has a circular central disc up to 35 mm ( ...
'' (
Ophiurida The Ophiurida are an order of echinoderms within the class Ophiuroidea. It includes the vast majority of living brittle stars. Characteristics Ophiurida have bursae for respiration and excretion, and dorsal and ventral arm shields are present a ...
) Image:Ophiolepis elegans 600.jpg, '' Ophiolepis elegans'' (
Amphilepidida Amphilepidida is an order of echinoderms belonging to the class Ophiuroidea. Families: * Amphilepididae * Amphilimnidae * Amphiuridae * Hemieuryalidae * Ophiactidae * Ophiolepididae * Ophionereididae Ophionereididae are a family of brittle st ...
) Image:Ophiure noire à la Réunion.JPG, ''
Ophiocoma erinaceus ''Ophiocoma erinaceus'' is a species of echinoderms An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, ...
'' (
Ophiacanthida Ophiacanthida is an order of echinoderms belonging to the class Ophiuroidea. Families: * Ophiodermatina Ljungman, 1867 ** Ophiodermatidae ** Ophiomyxidae ** Ophiopezidae ** Ophiocomidae Ophiocomidae are a family of brittle stars of the subo ...
) Image:Ophioleuce seminudum (MNHN-IE-2013-10292) 02.jpg, ''
Ophioleuce seminudum ''Ophioleuce'' is a genus of brittle stars. References * Thuy B, Gale AS, Kroh A, Kucera M, Numberger-Thuy LD, Reich M, et al. (2012) Ancient Origin of the Modern Deep-Sea Fauna. PLoS ONE 7(10): e46913. doi:10.1371/journal.pone.0046913 Op ...
'' ( Ophioleucida) Image:Ophiomyces frutectosus (MNHN-IE-2013-10282) 02.jpg, '' Ophiomyces frutectosus'' (
Ophioscolecida Ophioscolecida is an order of echinoderms belonging to the class Ophiuroidea. Families: * Ophiohelidae Ophiohelidae is a family of echinoderms belonging to the order Ophioscolecida. Genera: * '' Ophiohelus'' Lyman, 1880 * '' Ophiomyces'' L ...
)


Class Asteroidea ( Starfish)

*Infraclass
Concentricycloidea Sea daisies (infraclass Concentricycloidea; order Peripodida) make up an unusual group of deep-sea taxa belonging to the phylum Echinodermata, with three species described in the genus ''Xyloplax''. Intestine and anus are absent. Distribution S ...
** Peripodida *Superorder
Forcipulatacea The Forcipulatacea are a superorder of sea stars. Subdivision * order Forcipulatida * order Brisingida The Brisingids are deep-sea-dwelling starfish in the order Brisingida. Description These starfish have between 6 to 18 long, attenuated ...
**
Brisingida The Brisingids are deep-sea-dwelling starfish in the order Brisingida. Description These starfish have between 6 to 18 long, attenuated arms which they use for suspension feeding. Other characteristics include a single series of marginals, a f ...
**
Forcipulatida The Forcipulatida are an order of sea stars, containing three families and 49 genera. Description Forcipulatids share with the brisingid sea stars distinctive pedicellariae, consisting of a short stalk with three skeletal ossicles. Unlike tha ...
*Superorder Spinulosacea **
Spinulosida The Spinulosida are an order of sea stars containing at least 120 species in seven genera and one family. Spinulosids completely lack pedicellariae and have a delicate skeletal arrangement. Their name comes from the presence of numerous low spi ...
*Superorder Valvatacea **
Notomyotida Benthopectinidae is a family of sea stars containing at least 75 species in eight genera. It is the only family in the monotypic order Notomyotida. These asteroids are deep-sea dwelling and have flexible arms. The inner dorso-lateral surface ...
**
Paxillosida The Paxillosida are a large order of sea stars. Characteristics Paxillosida adults lack an anus and have no suckers on their tube feet. They do not develop the brachiolaria stage in their early development.Matsubara, M., Komatsu, M., Araki, T., ...
**
Valvatida The Valvatida are an order of starfish in the class Asteroidea, which contains 695 species in 172 genera in 17 families. Description The order encompasses both tiny species, which are only a few millimetres in diameter, like those in the gen ...
*
Velatida The Velatida are an order of sea stars containing about 200 species in five families. These sea stars normally have thick bodies with large discs. Description and characteristics This order contains mostly deep or cold seas sea stars, often w ...
* † Calliasterellidae * † Trichasteropsida Image:Xyloplax janetae.jpg, '' Xyloplax janetae'' ( Peripodida) Image:Brisingid Seastar (Novodinia antillensis).jpg, '' Novodinia antillensis'' (
Brisingida The Brisingids are deep-sea-dwelling starfish in the order Brisingida. Description These starfish have between 6 to 18 long, attenuated arms which they use for suspension feeding. Other characteristics include a single series of marginals, a f ...
) Image:Starfish, Oregon coast.jpg, ''
Pisaster ochraceus ''Pisaster ochraceus'', generally known as the purple sea star, ochre sea star, or ochre starfish, is a common seastar found among the waters of the Pacific Ocean. Identified as a keystone species, ''P. ochraceus'' is considered an important indi ...
'' (
Forcipulatida The Forcipulatida are an order of sea stars, containing three families and 49 genera. Description Forcipulatids share with the brisingid sea stars distinctive pedicellariae, consisting of a short stalk with three skeletal ossicles. Unlike tha ...
) Image:Echinaster sepositus Banyuls 03.jpg, '' Echinaster sepositus'' (
Spinulosida The Spinulosida are an order of sea stars containing at least 120 species in seven genera and one family. Spinulosids completely lack pedicellariae and have a delicate skeletal arrangement. Their name comes from the presence of numerous low spi ...
) Image:Cheiraster echinulatus.jpg, '' Cheiraster echinulatus'' (
Notomyotida Benthopectinidae is a family of sea stars containing at least 75 species in eight genera. It is the only family in the monotypic order Notomyotida. These asteroids are deep-sea dwelling and have flexible arms. The inner dorso-lateral surface ...
) Image:Astropecten aranciacus Sardegna09 28cm 5520.jpg, ''
Astropecten aranciacus ''Astropecten aranciacus'', the red comb star, is a sea star of the family Astropectinidae. It is native to the east Atlantic Ocean (Portugal to Angola) and Mediterranean Sea. Habitat and behaviour ''Astropecten aranciacus'' lives very near the ...
'' (
Paxillosida The Paxillosida are a large order of sea stars. Characteristics Paxillosida adults lack an anus and have no suckers on their tube feet. They do not develop the brachiolaria stage in their early development.Matsubara, M., Komatsu, M., Araki, T., ...
) Image:Linckia laevigata Tonga.jpg, '' Linckia laevigata'' (
Valvatida The Valvatida are an order of starfish in the class Asteroidea, which contains 695 species in 172 genera in 17 families. Description The order encompasses both tiny species, which are only a few millimetres in diameter, like those in the gen ...
) Image:Euretaster insignis.jpg, ''
Euretaster insignis ''Euretaster insignis'', commonly known as the striking sea star, is a species of starfish in the family Pterasteridae found in the central west Pacific Ocean. It is one of only three species in the order Velatida to be found in shallow water in ...
'' (
Velatida The Velatida are an order of sea stars containing about 200 species in five families. These sea stars normally have thick bodies with large discs. Description and characteristics This order contains mostly deep or cold seas sea stars, often w ...
)


Subphylum

Echinozoa Echinozoa is a subphylum of free-living echinoderms in which the body is or originally was a modified globe with meridional symmetry. Echinozoans lack arms, brachioles, or other appendages, and do not at any time exhibit pinnate structure. Their t ...


Class Echinoidea (

Sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) ...
s)

** Order Diadematoida ** Order
Echinothurioida The Echinothurioida are an order of sea urchins in the class Echinoidea. Echinothurioids are distinguished from other sea urchins by the combination of a flexible test and hollow spines. The membrane around the mouth contains only simple plates ...
** Order
Pedinoida Pedinoida is an order of sea urchins, containing the single living genus '' Caenopedina''. The group was much more diverse during the Mesozoic, and represents the oldest surviving order of euechinoid sea urchins. They are distinguished from ot ...
* Superorder
Echinacea ''Echinacea'' is a genus of herbaceous flowering plants in the daisy family. It has ten species, which are commonly called coneflowers. They are found only in eastern and central North America, where they grow in moist to dry prairies and op ...
** Order Arbacioida ** Order
Echinoida Echinoida is an order of sea urchins in the class Echinoidea. They are distinguished from other sea urchins by simultaneously possessing both an un-sculpted test and a feeding lantern with large plates fused across the top of each pyramid. Tax ...
** Order
Phymosomatoida The Phymosomatoida are an order of sea urchins, found in Europe, North America, North Africa and the Middle East. They are distinguished from other sea urchins by the presence of large fused plates on top of the feeding lantern. The test is usua ...
** Order
Salenioida The Salenioida are an order of sea urchins. Description and characteristics They are distinguished from other sea urchins by the presence of a large plate on the upper surface, with the anus to one side. They have very large tubercles between ...
** Order
Temnopleuroida Temnopleuridea is an infraorder of sea urchins in the order Camarodonta. They are distinguished from other sea urchins by the presence of large fused plates on top of the feeding lantern. The test is usually sculpted to some degree, and has perf ...
* Superorder
Gnathostomata Gnathostomata (; from Greek: (') "jaw" + (') "mouth") are the jawed vertebrates. Gnathostome diversity comprises roughly 60,000 species, which accounts for 99% of all living vertebrates, including humans. In addition to opposing jaws, livi ...
** Order
Clypeasteroida Sand dollars (also known as a sea cookie or snapper biscuit in New Zealand, or pansy shell in South Africa) are species of flat, burrowing sea urchins belonging to the order Clypeasteroida. Some species within the order, not quite as flat, are k ...
(sand dollars) ** Order
Holectypoida The Holectypoida are an order of sea urchins related to the sand dollars. The order consists of just two living genera, but was once more diverse. Description and characteristics In appearance, the living holectypoids are similar to sand dollar ...
* Superorder
Atelostomata The Atelostomata are a type of sea urchins. They are distinguished from other sea urchins by their irregular shape and the absence of a feeding lantern. The group includes the well known heart urchins, as well as some less familiar and extinct fo ...
** Order
Holasteroida Holasteroida is an order of irregular sea urchins. Characteristics These irregular sea urchins are characterized by a particularly marked bilateral symmetry, including for the apical system, which is highly elongated. In some contemporary aby ...
** Order
Spatangoida The heart urchins or Spatangoida are an order of sea urchins. Their body is a somewhat elongated oval in form, and is distinguished by the mouth being placed towards one end of the animal, and the anus towards the other. As a result, heart urchi ...
(heart urchins) Image:Aspidodiadema arcitum.jpg, ''
Aspidodiadema hawaiiense ''Aspidodiadema hawaiiense'' is a species of sea urchin of the family Aspidodiadematidae. Their armor is covered with spines. It is placed in the genus Aspidodiadema and lives in the sea. Aspidodiadema hawaiiense was first scientifically describ ...
'', an
Aspidodiadematoida The Aspidodiadematidae are a family of sea urchins. Characteristics All the members of the two extant genera, ''Aspidodiadema'' and ''Plesiodiadema'', are found in tropical seas at bathyal and abyssal depths, often on the submarine slopes of i ...
Image:Diadema antillarum Flower Garden Banks.jpg, ''
Diadema antillarum ''Diadema antillarum'', also known as the lime urchin, black sea urchin, or the long-spined sea urchin, is a species of sea urchin in the family Diadematidae. This sea urchin is characterized by its exceptionally long black spines. It is the ...
'', a Diadematoida Image:Caenopedina hawaiiensis.jpg, ''
Caenopedina hawaiiensis ''Caenopedina hawaiiensis'' is a species of sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertida ...
'', a
Pedinoida Pedinoida is an order of sea urchins, containing the single living genus '' Caenopedina''. The group was much more diverse during the Mesozoic, and represents the oldest surviving order of euechinoid sea urchins. They are distinguished from ot ...
Image:Salenocidaris hastigera.png, '' Salenocidaris hastigera'', a
Salenioida The Salenioida are an order of sea urchins. Description and characteristics They are distinguished from other sea urchins by the presence of a large plate on the upper surface, with the anus to one side. They have very large tubercles between ...
Image:Arbacia lixula (oursin noir).JPG, '' Arbacia lixula'', an Arbacioida Image:Strongylocentrotus franciscanus at Telegraph Cove.jpg, '' Strongylocentrotus franciscanus'', a
Camarodonta The Camarodonta are an order of globular sea urchins in the class Echinoidea. The fossil record shows that camarodonts have been in existence since the Lower Cretaceous.Stomopneustes variolaris'', a
Stomopneustoida Stomopneustoida is an order of echinoderms belonging to the class Echinoidea Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zo ...
Image:Toxic Leather Sea Urchin - Asthenosoma marisrubri.jpg, '' Asthenosoma marisrubri'', an
Echinothurioida The Echinothurioida are an order of sea urchins in the class Echinoidea. Echinothurioids are distinguished from other sea urchins by the combination of a flexible test and hollow spines. The membrane around the mouth contains only simple plates ...
Image:Pourtalesia wandeli.png, '' Pourtalesia wandeli'', a
Holasteroida Holasteroida is an order of irregular sea urchins. Characteristics These irregular sea urchins are characterized by a particularly marked bilateral symmetry, including for the apical system, which is highly elongated. In some contemporary aby ...
Image:Tiny maretia heart urchin (Maretia planulata).jpg, ''
Maretia planulata ''Maretia'' is a genus of heart urchins belonging to the family Spatangidae. Species * '' Maretia carinata'' Bolau, 1873 * '' Maretia cordata'' Mortensen, 1948 * '' Maretia estenozi'' Sánchez Roig, 1926 * ''Maretia planulata'' ( Lamarck, 181 ...
'', a
Spatangoida The heart urchins or Spatangoida are an order of sea urchins. Their body is a somewhat elongated oval in form, and is distinguished by the mouth being placed towards one end of the animal, and the anus towards the other. As a result, heart urchi ...
Image:Echinoneus cyclostomus.jpg, '' Echinoneus cyclostomus'', an
Echinoneoida Echinoneoida is an order of echinoderms belonging to the class Echinoidea Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zon ...
Image:Clypeaster reticulatus.jpg, '' Clypeaster reticulatus'', a
Clypeasteroida Sand dollars (also known as a sea cookie or snapper biscuit in New Zealand, or pansy shell in South Africa) are species of flat, burrowing sea urchins belonging to the order Clypeasteroida. Some species within the order, not quite as flat, are k ...
Image:Echinolampas depressa.png, ''
Echinolampas depressa ''Echinolampas'' is a genus of echinoderms belonging to the family Echinolampadidae. The genus has cosmopolitan distribution. Species: *'' Echinolampas africana'' *'' Echinolampas aldrichi'' *'' Echinolampas alexandri'' *'' Echinolampas alt ...
'', an Echinolampadoida Image:Eucidaris metularia à la Réunion.jpg, '' Eucidaris metularia'', a
Cidaroida Cidaroida is an order of primitive sea urchins, the only living order of the subclass Perischoechinoidea. All other orders of this subclass, which were even more primitive than the living forms, became extinct during the Mesozoic. Description T ...


Class Holothuroidea (

Sea cucumber Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothu ...
s)

** Order
Apodida Apodida is an order of littoral to deep-sea, largely infaunal holothurians, sea cucumbers. This order comprises three families, 32 genera and about 270 known species, called apodids, "without feet". Characteristics These sea cucumbers are vagil ...
** Order
Dendrochirotida Dendrochirotida are an order of sea cucumbers. Members of this order have branched tentacles and are suspension feeders. Examples include '' Thyonella'' and ''Cucumaria''. Characteristics Holothurians in this order are characterised by ten to th ...
** Order
Elasipodida Elasipodida is an order of sea cucumbers. They have numerous appendages, including conical papillae and leaf-like tentacles. Although many species are benthic, a number are pelagic, and may have their appendages modified to form sails or fins. Mo ...
** Order
Holothuriida Holothuriida is an order of sea cucumbers. Taxa within the order Holothuriida were previously classified in the order Aspidochirotida, which was determined to be polyphyletic in 2017. Some taxa were also reclassified into the clades Synallactida ...
** Order
Molpadida Molpadida is an order of sea cucumbers. The body shape is fusiform and unlike other sea cucumbers, their hind body is narrowed to form a distinct tail. Although they possess tentacles around the mouth derived from the water vascular system, they ...
** Order
Persiculida Persiculida is an order of sea cucumbers. Taxa within the order Persiculida were previously classified in an order called Aspidochirotida, which was determined to be polyphyletic A polyphyletic group is an assemblage of organisms or other ev ...
** Order
Synallactida Synallactida is a rankless clade of sea cucumbers, but is referred to as an order. Taxa within Synallactida were previously classified in an order called Aspidochirotida, which was determined to be polyphyletic in 2017. List of families Synal ...
{{clr Image:Euapta godeffroyi1.jpg, ''
Euapta godeffroyi ''Euapta godeffroyi'', the sticky snake sea cucumber, is a species of sea cucumber in the family Synaptidae Synaptidae is a family of sea cucumbers that have no tube feet, tentacle ampullae, retractor muscles, respiratory trees, or cuvierian ...
'' (
Apodida Apodida is an order of littoral to deep-sea, largely infaunal holothurians, sea cucumbers. This order comprises three families, 32 genera and about 270 known species, called apodids, "without feet". Characteristics These sea cucumbers are vagil ...
) Image:Cercodemas anceps Red box sea cucumber PC260152.JPG, '' Cercodemas anceps'' (
Dendrochirotida Dendrochirotida are an order of sea cucumbers. Members of this order have branched tentacles and are suspension feeders. Examples include '' Thyonella'' and ''Cucumaria''. Characteristics Holothurians in this order are characterised by ten to th ...
) Image:Scotoplanes globosa and crab.jpg, ''
Scotoplanes globosa ''Scotoplanes globosa,'' commonly known as the sea pig, is a species of sea cucumber that lives in the deep sea. It was first described by Hjalmar Théel, a Swedish scientist. ''Scotoplanes globosa'', along with numerous other sea cucumbers wer ...
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Elasipodida Elasipodida is an order of sea cucumbers. They have numerous appendages, including conical papillae and leaf-like tentacles. Although many species are benthic, a number are pelagic, and may have their appendages modified to form sails or fins. Mo ...
) Image:Holothuria cinerascens Réunion.jpg, ''
Holothuria cinerascens ''Holothuria'' (''Semperothuria'') ''cinerascens'' is a species of sea cucumber in the family Holothuriidae. The sea cucumber is widely distributed in the Pacific and Indian ocean, being found from the Red Sea to Madagascar and from Japan to Austra ...
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Holothuriida Holothuriida is an order of sea cucumbers. Taxa within the order Holothuriida were previously classified in the order Aspidochirotida, which was determined to be polyphyletic in 2017. Some taxa were also reclassified into the clades Synallactida ...
) Image:See-through sea cucumber (Paracaudina australis).jpg, '' Paracaudina australis'' (
Molpadida Molpadida is an order of sea cucumbers. The body shape is fusiform and unlike other sea cucumbers, their hind body is narrowed to form a distinct tail. Although they possess tentacles around the mouth derived from the water vascular system, they ...
) Image:Hansenothuria benti.png, '' Hansenothuria benti'' (
Persiculida Persiculida is an order of sea cucumbers. Taxa within the order Persiculida were previously classified in an order called Aspidochirotida, which was determined to be polyphyletic A polyphyletic group is an assemblage of organisms or other ev ...
) Image:Stichopus herrmanni (Mayotte).jpg, '' Stichopus herrmanni'' (
Synallactida Synallactida is a rankless clade of sea cucumbers, but is referred to as an order. Taxa within Synallactida were previously classified in an order called Aspidochirotida, which was determined to be polyphyletic in 2017. List of families Synal ...
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Class

Ophiocistioidea The Ophiocistioidea is a class of extinct echinoderms from the Palaeozoic and early Mesozoic. Ophiocistioids had a flattened dome-shaped body encased in a solid test of calcareous plates, similar to that of a modern sea urchin. The mouth was at ...
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No orders recognized: class is divided up into four
families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
, Eucladiidae, Sollasiniidae, Volchoviidae, and Rhenosquamidae. The inclusion of Rhenosquamidae within Ophiocistioidea is doubtful, as the organs identified in fossils of '' Rhenosquamus'' as the characteristic "scaly podia" otherwise diagnostic of ophiocistioids may not, in fact, be such structures.


Class

Helicoplacoidea Helicoplacoidea is an extinct class within the Echinodermata. All known taxa were discovered in sediments dating back to the Cambrian.
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No known orders, 2 known species, ''Helicoplacus curtisi'' and ''H. guthi''


Subphylum

Blastozoa Blastozoa is a subphylum of extinct animals belonging to Phylum Echinodermata. This subphylum is characterized by the presence of specialized respiratory structures and brachiole plates used for feeding. This subphylum ranged from the Cambrian to ...


Class

Blastoidea Blastoids (class Blastoidea) are an extinct type of stemmed echinoderm, often referred to as sea buds. They first appear, along with many other echinoderm classes, in the Ordovician period, and reached their greatest diversity in the Mississi ...
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* Ordre Coronata † * Order Fissiculata † * Order Spiraculata † * basal '' Macurdablastus'' †


Class

Eocrinoidea The Eocrinoidea are an extinct class of echinoderms that lived between the Early Cambrian and Late Silurian periods. They are the earliest known group of stalked, arm-bearing echinoderms, and were the most common echinoderms during the Cambrian. ...
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* Order Ascocystida † * Order Gogiida † * Order Imbricata † * Order Trachelocrinida †


Subphylum Homostelea /

Homalozoa Homalozoa is an obsolete extinct subphylum of Paleozoic era echinoderms, prehistoric marine invertebrates. They are also referred to as carpoids. Description The Homalozoa lacked the typical pentamer body form of other echinoderms, but all ...
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Class

Ctenocystoidea Ctenocystoidea is an extinct clade of echinoderms, which lived during the Cambrian and Ordovician periods. Unlike other echinoderms, ctenocystoids had bilateral symmetry, or were only very slightly asymmetrical. They are believed to be one of th ...
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** order Ctenocystida †


Class Soluta †


Class

Cincta Cincta is an extinct class of echinoderms that lived only in the Middle Cambrian epoch. Homostelea is a junior synonym. The classification of cinctans is controversial, but they are probably part of the echinoderm stem group. Cinctans were sessi ...
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Class

Stylophora The stylophorans are an extinct, possibly polyphyletic group allied to the Paleozoic Era echinoderms, comprising the prehistoric cornutes and mitrates. It is synonymous with the subphylum Calcichordata. Their unusual appearances have led to a v ...
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** order Cornuta † ** order
Mitrata Mitrates are an extinct group of stem group echinoderms, which may be closely related to the hemichordates. Along with the cornutes, they form one half of the Stylophora. Morphology The organisms were a few millimetres long. Like the echinoder ...
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References

List
Orders Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...